Legal claims defining the scope of protection. Each claim is shown in both the original legal language and a plain English translation.
1. A method comprising: receiving at least two audio channel signals; scalar quantizing a parameter to generate an index value wherein the parameter represents a difference between the at least two audio channel signals and comprises at least one of an interaural time difference or an interaural level difference; determining a frequency distribution of index values by maintaining a running count of index values, wherein the running count of index values associated with past indices are weighted downwards by a recurrence factor which is less than one; reordering the index value dependent on the frequency distribution of index values to generate a reordered index value; encoding the reordered index value dependent on an order position of the reordered index value; generating a single channel representation of the at least two audio channel signals dependent on the at least one parameter; and encoding the single channel representation.
A method for encoding stereo audio signals involves analyzing the differences between the left and right audio channels. It first quantizes a parameter, which represents either the time difference or the level difference between the channels, and assigns an index value to it. The method then tracks how frequently each index value occurs, giving more weight to recent values than to older ones. Based on this frequency distribution, the index values are reordered. Finally, the reordered index value is encoded based on its new position in the order, and a single combined audio channel is created and encoded. This process compresses the stereo audio while preserving spatial information.
2. The method as claimed in claim 1 , wherein scalar quantizing a parameter further comprises: ordering the scalar quantized output according to a predetermined map.
The method for encoding stereo audio signals, including quantizing a parameter (representing interaural time or level difference) to generate an index, determining a frequency distribution of indices with weighted past values, reordering the index based on the distribution, encoding the reordered index based on its position, and encoding a single channel representation; refines the initial quantization step. Specifically, after the scalar quantization process, the resulting output (the index value) is further processed by ordering it according to a pre-defined map or table. This pre-defined map ensures a consistent and optimized representation of the quantized parameter before subsequent processing stages.
3. The method as claimed in claim 2 , wherein determining a frequency distribution of index values by maintaining a running count of index values where the past indices are weighted downwards by a recurrence factor further comprises: receiving a group of index values; increasing a count value associated with a first index value; and decreasing a count value associated with index values other than the first index value.
The method for encoding stereo audio signals, including quantizing a parameter (representing interaural time or level difference) to generate an index, determining a frequency distribution of indices with weighted past values, reordering the index based on the distribution, encoding the reordered index based on its position, and encoding a single channel representation; refines the frequency distribution calculation. Instead of simply counting occurrences, the method operates on groups of index values. When a new index value is encountered, its corresponding count is incremented. Simultaneously, the counts of other index values within the group are decremented. This creates a dynamic and relative frequency distribution that adapts quickly to changes in the audio signal.
4. The method as claimed in claim 1 , wherein encoding the reordered index value dependent on an order position of the reordered index value comprises applying a Golomb-Rice encoding to the reordered index value dependent on the reordered index value order position.
The method for encoding stereo audio signals, including quantizing a parameter (representing interaural time or level difference) to generate an index, determining a frequency distribution of indices with weighted past values, reordering the index based on the distribution, encoding the reordered index based on its position, and encoding a single channel representation; specifies the type of encoding used for the reordered index. A Golomb-Rice encoding technique is applied to the reordered index value. The specific parameters of the Golomb-Rice encoding are determined by the reordered index value's position or order within the frequency distribution. This adaptive encoding efficiently compresses the reordered index values.
5. A method comprising: decoding from a first part of a signal an index value of a parameter instance, wherein the parameter represents a difference between at least two audio channel signals and comprises at least one of an interaural time difference and an interaural level difference, and wherein the signal is an encoded multichannel audio signal; determining a frequency distribution of index values by maintaining a running count of index values, wherein the running count of index values associated with past indices are weighted downwards by a recurrence factor which is less than one; reordering the index values to generate a reordered index value, wherein the reordering is dependent on the frequency distribution of reordered index values; and dequantizing the reordered index value to generate the parameter.
A method for decoding a stereo audio signal that was previously encoded focuses on extracting spatial information. It starts by decoding an index value from the encoded signal, where this index represents either the time difference or the level difference between the original left and right audio channels. The method then tracks the frequency of occurrence of these index values, prioritizing recent values over older ones. Based on this frequency distribution, the index values are reordered. Finally, the reordered index value is dequantized to reconstruct the original interaural time or level difference parameter. This allows for the reconstruction of the original stereo image.
6. The method as claimed in claim 5 , wherein decoding from a first part of a signal an index of a parameter comprises decoding a first part of a signal using a Golomb-Rice decoding.
The method for decoding a stereo audio signal, including decoding an index representing interaural time/level difference, determining a frequency distribution of indices with weighted past values, reordering indices based on the distribution, and dequantizing the reordered index; details the initial decoding step. Specifically, the process of decoding the index value from the encoded signal uses a Golomb-Rice decoding technique. This corresponds to the Golomb-Rice encoding potentially used during the encoding phase, ensuring compatibility and proper extraction of the index.
7. The method as claimed in claim 6 , wherein determining the frequency distribution of the reordered index value comprises maintaining a count of the reordered index value for a group of the reordered index value.
The method for decoding a stereo audio signal, including decoding an index representing interaural time/level difference, determining a frequency distribution of indices with weighted past values, reordering indices based on the distribution, and dequantizing the reordered index; clarifies how the frequency distribution of reordered index values is determined. It involves maintaining a count for each reordered index value within a defined group or window of reordered index values. This localized counting approach allows the decoder to dynamically adapt to changing statistical properties of the reordered indices.
8. The method as claimed in claim 5 , wherein the reordered index value comprises: determining an inverse ordering dependent on a decreasing occurrence order mapping for the frequency distribution of reordered index values; and applying the inverse ordering.
The method for decoding a stereo audio signal, including decoding an index representing interaural time/level difference, determining a frequency distribution of indices with weighted past values, reordering indices based on the distribution, and dequantizing the reordered index; specifies how the reordering of index values is reversed during decoding. An inverse ordering is determined based on a mapping that reflects the decreasing order of occurrence of the reordered index values. This means the most frequent reordered index values are mapped back to their original positions or values. Then, this inverse ordering is applied to restore the original sequence of index values.
9. An apparatus comprising at least one processor and at least one memory including computer program code for one or more programs, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: receiving at least two audio channel signals; scalar quantize a parameter to generate an index value wherein the parameter is a difference between the at least two channel audio signals comprising at least one of an interaural time difference and an interaural level difference; determine a frequency distribution of index values by maintaining a running count of index values , wherein the running count of index values associated with past indices are weighted downwards by a recurrence factor which is less than one; reorder the index value dependent on the frequency distribution of index values to generate a reordered index value; encode the reordered index value dependent on an order position of the reordered index value; generate a single channel representation of the at least two audio channel signals dependent on the at least one parameter; and encode the single channel representation.
An apparatus for encoding stereo audio signals includes a processor and memory configured to perform the following steps: It receives two audio channel signals (left and right). It then quantizes a parameter representing the difference between the two channels (either time or level difference) to generate an index value. A frequency distribution of these index values is tracked, with more weight given to recent values. The index values are then reordered based on their frequency. The reordered index value is encoded depending on its position in the order. Finally, a single channel representation of the two audio channels is generated based on the parameter, and this single channel is also encoded.
10. The apparatus as claimed in claim 9 , wherein the apparatus caused to scalar quantize a parameter is further caused to: order the scalar quantized output according to a predetermined map.
The apparatus for encoding stereo audio signals, including quantizing a parameter (representing interaural time or level difference) to generate an index, determining a frequency distribution of indices with weighted past values, reordering the index based on the distribution, encoding the reordered index based on its position, and encoding a single channel representation; refines the initial quantization step. After the scalar quantization, the output (index value) is ordered according to a pre-determined map, optimizing the representation before further processing.
11. The apparatus as claimed in claim 10 , wherein the apparatus caused to determine a frequency distribution of index values by maintaining a running count of index values where the past indices are weighted downwards by a recurrence factor further comprises: receive a group of index values; increase a count value associated with a first index value; and decrease a count value associated with index values other than the first index value.
The apparatus for encoding stereo audio signals, including quantizing a parameter (representing interaural time or level difference) to generate an index, determining a frequency distribution of indices with weighted past values, reordering the index based on the distribution, encoding the reordered index based on its position, and encoding a single channel representation; refines the frequency distribution calculation. It receives a group of index values, increases a count value associated with the first index value in the group, and decreases the count values associated with the other index values in that group. This creates a dynamic and adaptive frequency distribution.
12. The apparatus as claimed in claim 9 , wherein the apparatus caused to encode the reordered index value dependent on an order position of the reordered index value is further caused to apply a Golomb-Rice encoding to the reordered index value dependent on the reordered index value order position.
The apparatus for encoding stereo audio signals, including quantizing a parameter (representing interaural time or level difference) to generate an index, determining a frequency distribution of indices with weighted past values, reordering the index based on the distribution, and encoding a single channel representation; specifies the type of encoding used for the reordered index. It applies a Golomb-Rice encoding to the reordered index value. The Golomb-Rice encoding is dependent on the order position of the reordered index value.
13. An apparatus comprising at least one processor and at least one memory including computer program code for one or more programs, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: decode from a first part of a signal an index value of a parameter instance, wherein the parameter represents a difference between at least two audio channel signals and comprises at least one of an interaural time difference or an interaural level difference, and, wherein the signal is an encoded multichannel audio signal; determine a frequency distribution of index values by maintaining a running count of index values, wherein the running count of index values associated with past indices are weighted downwards by a recurrence factor which is less than one; reorder the index values to generate a reordered index value, wherein the reorder is dependent on the frequency distribution of reordered index values; and dequantize the reordered index value to generate the parameter.
An apparatus for decoding a stereo audio signal that was previously encoded includes a processor and memory configured to perform the following steps: It decodes an index value representing the difference between two audio channels (time or level difference) from an encoded multichannel audio signal. It determines a frequency distribution of index values, weighting recent values more heavily. It reorders the index values based on this frequency distribution. Finally, it dequantizes the reordered index value to reconstruct the original parameter (time or level difference).
14. The apparatus as claimed in claim 13 , where the apparatus caused to decode from a first part of a signal an index of a parameter comprises decoding a first part of a signal using a Golomb-Rice decoding.
The apparatus for decoding a stereo audio signal, including decoding an index representing interaural time/level difference, determining a frequency distribution of indices with weighted past values, reordering indices based on the distribution, and dequantizing the reordered index; details the initial decoding step. It decodes the index from the encoded signal using a Golomb-Rice decoding.
15. The apparatus as claimed in claim 14 , wherein the apparatus caused to determine the frequency distribution of the reordered index value is further causes to maintain a count of the reordered index value for a group of the reordered index value.
The apparatus for decoding a stereo audio signal, including decoding an index representing interaural time/level difference, determining a frequency distribution of indices with weighted past values, reordering indices based on the distribution, and dequantizing the reordered index; clarifies how the frequency distribution of reordered index values is determined. It maintains a count of the reordered index value for a group of the reordered index values.
16. The apparatus as claimed in claim 13 , wherein the apparatus caused to reorder index values is further caused to: determine an inverse ordering dependent on a decreasing occurrence order mapping for the frequency distribution of reordered index values; and apply the inverse ordering.
The apparatus for decoding a stereo audio signal, including decoding an index representing interaural time/level difference, determining a frequency distribution of indices with weighted past values, reordering indices based on the distribution, and dequantizing the reordered index; specifies how the reordering of index values is reversed during decoding. It determines an inverse ordering based on a decreasing occurrence order mapping for the frequency distribution of reordered index values, and then applies this inverse ordering to reconstruct the original index sequence.
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October 24, 2017
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